1. Field of the Invention
The present invention relates to a mounting structure for a gas adsorption filter and to a housing equipped with a gas adsorption filter, and more particularly to a mounting structure for a gas adsorption filter and to a housing equipped with a gas adsorption filter in which an airtight container that needs to be protected from contamination by dust, corrosive gas, humidity, or the like is designed such that much less space is needed to accommodate the essential functional components disposed in the interior, and the contaminants can be adsorbed and removed with exceptional efficiency.
2. Description of Related Art
Magnetic storage disk devices such as computer hard drives (also referred to herein below as xe2x80x9cHDDsxe2x80x9d) are extremely sensitive to chemical contamination. High-molecular-weight organic vapors are adsorbed on the extremely smooth surfaces of disks, impeding the read performance of the head and causing head crashes. Other types of chemical contaminants (for example, SO2) sometimes bring about metallurgical changes in disks and magnetic heads, and particularly corrosion in magnetic-resistance read elements. In conventional practice, HDDs are fashioned as completely sealed structures in order to prevent such corrosive gases from penetrating from the outside. Recently, however, a transition has been made to manufacturing top covers from press-formed stainless steel plates, but since strain is generated in completely sealed containers due to volume variations induced by temperature changes causing head crashes, case deformations, and other problems, methods in which ventilation ports are provided to adjust the pressure inside the container have been widely adopted. Gas adsorption filters obtained by integrating gas adsorbents and particle filters are also used on a wide scale in order to prevent microparticles and corrosive gases from penetrating through the ventilation ports from the outside. Such gas adsorption filters are designed such that the ventilation ports are completely covered with an activated carbon sheet or the like, and any noxious gas that has seeped in is removed by being passed through a gas adsorbent layer.
The storage capacity of HDDs has increased dramatically in recent years. The storage capacity of an HDD with a single media (3.5-inch disk) currently reaches 40 GB and is projected to reach 100 GB in the near future. Even as the storage capacity of HDDs keeps increasing, their prices remain on the same level, confronting HDD manufacturers with the important task of seeking out ways to remain profitable. At the same time, HDD miniaturization continues with the popularization of notebook computers, PDAs, and other mobile computers. The race for HDD miniaturization has recently intensified due to increased storage capacity, lower prices, a push by the manufacturers to expand into new markets, and other trends. An HDD with a 1-inch disk was developed and put on the market last year by IBM, as was an HDD with a 1.8-inch disk by Toshiba. Even HDD manufacturers who until now did not have HDDs with 2.5-inch disks in their product lineup are starting to develop HDDs with 2.5- and 1.8-inch disks. It appears certain that large numbers of HDD manufacturers are going to be involved in the manufacture and distribution of HDDs with disks that measure 2.5 inches or less.
To create miniature HDDs with disks that measure 2.5 inches or less, it is necessary to pack a large number of components into small containers, so securing the necessary space is a significant challenge. This is because the advantages of a miniature HDD include ease of handling, small size, and light weight, and devices are currently being designed with the objective of achieving minimum excess space and maximum compactness. There is, therefore, a strong need for component miniaturization.
Such miniature HDDs are primarily used in notebook computers, PDAs, and other applications in which portability is an important feature. Such devices are often operated in environments in which, for example, a device is carried around in the summer and is brought into an air-conditioned room after being exposed to high temperature and humidity, whereupon moisture condenses inside the HDD as a result of a rapid drop in temperature. Situations can also be envisaged in which such products are used at construction sites, at locations in which exhaust gas (SOx, NOx, organic gases) or the like is present, and in other environments with high concentrations of noxious gases or particles harmful to HDDs. Specifically, miniature HDDs can be exposed to the rigorous environments not encountered by desktop computers, making contamination control (particle collection, humidity adjustment by the release and absorption of moisture, adsorption and removal of noxious gas) a critical issue in terms of preserving vital functions. For this reason, miniature HDDs require smaller components, and the gas adsorption filters used to control contamination must at the same time have greater adsorption capacity, be capable of rapid contaminant removal (have appropriate response properties), and possess other improved characteristics. Currently, however, a conflict
There is substantially no space inside a miniature HDD, making it extremely difficult to install a gas adsorption filter capable of adequately adsorbing and removing corrosive gases or the like. With conventional techniques, it is extremely difficult to achieve a thickness of 0.6 mm or less, even in a minimal structure comprising an adhesive layer (which is used to affix the gas adsorption filter), a gas adsorbent layer, and a filter layer (which is used to prevent particle contamination), and any further reduction in film thickness brings about problems such as impaired handling during assembly, problems such as the failure to secure adequate adsorption performance due to reduced gas adsorbent capacity and the like.
An HDD rejected as a result of a pre-shipping inspection is retrieved, reworked (repaired and reassembled), re-inspected, and shipped. For this reason, each component needs to be washed, cleaned, and reused, and large numbers of components are actually used in this manner. The gas adsorption filters primarily used in current practice are mostly fixed in place with the aid of adhesives. Peeling off a gas adsorption filter for reworking purposes may deform the gas adsorption filter and allow part of the adhesive to remain on the adherend, creating problems not only in terms of reusing the gas adsorption filter but also in terms of reusing the adherend.
An HDD designed to allow gas adsorption filters to be reused has been marketed by IBM under the trade name of Ultrastar. FIG. 1 is a cross section depicting the mounting structure for a gas adsorption filter used in this type of HDD. In this mounting structure, the bottom of a plastic box 2 that forms the outside of a gas adsorption filter 1 is machined to form a convex portion 3, the gas adsorption filter 1 is dropped into a hole 9 formed in an HDD container 8 from outside the HDD, and the filter is fixedly sealed from the outside of the HDD by an adhesive tape 7. In the drawing, 4 is an adsorbent, 5 a breathable sheet, and 6 a ventilation port. This structure, however, is designed solely with the purpose of allowing the gas adsorption filter to be reused, and cannot be expected to be effective in terms of improved performance or reduced space. In practice, the sole difference of the gas adsorption filter used in IBM""s Deskstar from the one shown in FIG. 1 is the absence of the component 10 shaped as a circular truncated cone and disposed in the ventilation port 6. In this filter, an adhesive is applied to the top of the convex portion 3, and this adhesive is affixed to the inner wall of the HDD. Thus, a structure such as the one shown in FIG. 1 is substantially ineffective in terms of reducing space or improving adhesion performance.
As described above, the inside space of miniature HDDs is gradually decreasing. Trace amounts of corrosive gases are generated by the adhesives, plastics, motors, and other components disposed inside the HDDs. Although miniature HDDs contain fewer components than do HDDs with 3.5-inch disks, the concentration of gases generated inside such HDDs tends to increase because the interior space is extremely small. A need therefore exists for reducing, even if only slightly, the amount of gases generated by the components inside an HDD.
Providing the bottom part of a filter with a nonadhesive, nonporous base layer is proposed in U.S. Pat. No. 6,214,095 as a means of addressing this problem. In this technique, however, pins or folders are needed to fix a gas adsorption filter in place inside a disk drive without the use of an adhesive. This approach is therefore disadvantageous in that extra parts required incur higher costs, and additional time is needed to perform the fixing operation.
Overcoming the deficiencies of these prior art devices, as well as other purposes of the present invention will become evident from review of the following specification.
The present invention, which was perfected in view of the above-described shortcomings of the prior art, is aimed at providing a mounting structure for a gas adsorption filter and a housing equipped with the gas adsorption filter that make it possible to overcome the contradiction between achieving a further reduction in the size of airtight containers such as casings for magnetic storage disk devices, and ensuring improved control over moisture, noxious gases, and other types of contaminants in the airtight containers.
Another object of the present invention is to provide a mounting structure for a gas adsorption filter and a housing equipped with a gas adsorption filter in which the pressure loss can be kept at the same or lower level in comparison with a conventional gas adsorption filter, and the gas adsorption features can be kept at the same or higher level than in the past without requiring any modifications to the casing configuration of airtight containers or requiring any of the cost-enhancing plastic parts to be installed.
The inventors perfected the present invention as a result of extensive research aimed at overcoming the aforementioned shortcomings.
Specifically, the present invention provides a mounting structure for a gas adsorption filter and a housing equipped with a gas adsorption filter, as described below. The gas adsorption filter to be mounted in an airtight container is formed by providing an adsorbent to one or both sides of a base, covering the adsorbent with a breathable member to form an adsorbent unit, bonding together the breathable member and the peripheral portion of the base around the adsorbent to form a collar, fitting the adsorbent unit of the gas adsorption filter into a mounting hole formed in the airtight container, and bonding the collar of the gas adsorption filter to the peripheral portion of the mounting hole outside the airtight container. The breathable member is preferably a porous polymer film, and more preferably a laminated sheet comprising a porous polymer film and a breathable support. In an alternative embodiment, the breathable member is an adsorbent container at least partially composed of a porous polymer film, more preferably at least partially composed of a laminated sheet of porous polymer film and a breathable support. In a preferred embodiment, the porous polymer film comprises porous polytetrafluoroethylene film.
In further embodiments, the mounting structure may comprise one or more optional features such as ventilation ports formed in the base, the collar bonded to the peripheral portion of the mounting hole outside the airtight container, the base and the external surface of the airtight container covered with a cover sheet, the external surface of the base provided with a release layer, and the adsorbent provided with grooved air channels. These features will be described in more detail herein.
In a further embodiment, the invention is directed to a mounting structure for a gas adsorption filter to be mounted in an airtight container, wherein the gas adsorption filter comprises an adsorbent container unit that contains an adsorbent and consists at least partially of a breathable sheet, a projection formed on part of the side surface of the adsorbent container unit, wherein the adsorbent container unit below the projection on the gas adsorption filter is fitted into a mounting hole formed in the airtight container, and the projection on the gas adsorption filter is bonded to the peripheral portion of the mounting hole on the outside of the airtight container.
The breathable sheet may comprise a porous polymer film, more preferably a laminated sheet of porous polymer film and a breathable support, and most preferably wherein the porous polymer film is a porous polytetrafluoroethylene film.
Further, a housing containing such devices is disclosed and claimed.